This is an application requesting funds to purchase a Thermo Orbitrap Fusion Lumos Tribrid mass spectrometer and nanoflow liquid chromatography system that will be used for proteomics research. The instrument will be integrated into the Robert Wood Johnson Medical School/Rutgers University Biological Mass Spectrometry Facility in Piscataway New Jersey. There are two justifications for this request. First, current LC-MS instrumentation in the Facility (a Thermo Orbitrap Velos Pro and a Thermo Q-Exactive HF) are used at maximal capacity and we require additional instrument to meet the demands of our NIH-funded investigators. This situation will become critical as the Orbitrap Velos approaches the end of its useful operational life for cutting-edge research. Second, our NIH-supported User group requires mass spectrometry to address a wide range of specific diseases including asthma and respiratory disease, neurological disease, bacterial and viral infection, disruption of endocrine function, skin disorders, sleep disorders, diabetes, digestive disease, inflammation and cancer, as well as other fundamental issues of biomedical importance. While label-free options for quantitative mass spectrometry continue to hold promise, we have conducted benchmark studies that indicate that when conducted using suitable instrumentation, isobaric labeling approaches provide an optimal combination of accuracy, sensitivity, dynamic range and throughput. This is reflected by the increasing demand for isobaric labeling studies from our users that we have documented within this proposal. The Thermo Orbitrap Fusion instruments are the only mass spectrometers capable of high-accuracy, high-sensitivity measurement of isobaric reporter ions by virtue of their ability to conduct synchronous precursor selection for fragmentation of MS2 ions and measurement at the MS3 level. The requested instrument will represent a significant asset to our research community and will accelerate the pace of basic and applied biomedical research of NIH-funded investigators on the New Brunswick and Piscataway campuses of Rutgers, the State University of New Jersey.